Waveguides are widely used in different technology fields such as wireless and wire-line communications, metrology, sensing and security for guiding waves from one point to another. Generally, waveguides can be broadly classified as metallic waveguides and dielectric waveguides. These different waveguides have very different fundamental characteristics and wave guiding properties.
As the terahertz (THz) frequency range is located between the microwaves and optics regimes, emerging THz waveguide applications will naturally employ convergence of techniques from both of these regimes. Whilst the transition between optics and microwaves for most applications only require simple scaling, guided-wave applications between optics and microwaves often require the use of both metallic waveguides and dielectric waveguides that have drastically different wave guiding properties for transferring wave signals or power. Efficient wave signals or power transfer and coupling between these waveguides are critical to both the operation and the characterization of THz guided-wave systems.